Use of water-soluble polymers, such as hydroxyethyl-cellulose (HEC) and polyvinyl alcohol, as rheological modifiers of aqueous dispersions, such as protective coating compositions or latex paints, has found wide acceptance. The hydrophobically-modified cellulose ether derivatives modified with the long chain alkyl groups described by Landoll, in U.S. Pat. Nos. 4,228,277 and 4,352,916, have shown promise in many applications and one such polymer, a modified HEC, is presently sold under the Trademark Natrosol Plus by the Aqualon Company, Wilmington, DE. Latex paints prepared with this modified HEC perform extremely well compared to those prepared with other well known cellulosic polymers. There are many difficulties in producing such polymers. Use of long chain alkyl bromides to produce such polymers shows much promise but has a number of disadvantages, e.g., long chain alkyl bromides are not reactive enough and require long reaction times at high temperatures. In addition, high caustic levels must be used in production. Further, these polymers have high levels of hydroxyethyl groups, which cause the polymers to be hygroscopic in nature and have caking problems.
E. D. Klug, in "Some Properties of Water-Soluble Hydroxyalkyl Celluloses and Their Derivatives", Journal of Polymer Science, Volume 36, Part C, 491-508, at 497-98 (John Wiley & Sons, Inc. 1971), mentions lowering the cloud point of hydroxypropylcellulose and hydroxyethylcellulose by use of a long chain alkyl glycidyl ether such as decyl glycidyl ether.
It has been discovered that latex paints prepared with the modified hydroxyethylcellulose, i.e., 3-alkoxy-2-hydroxypropylhydroxyethylcellulose provide properties similar to unmodified cellulosic thickened latex paints with respect to thickening efficiency, leveling, 60.degree. gloss and color development. Property enhancements are obtained with respect to spatter resistance, sag resistance and high shear viscosity (ICI).
The polymers of this invention can be prepared using simpler processing techniques than those used to prepare the hydrophobically modified polymers described by Landoll. In addition, these polymers do not have the disadvantages of the Landoll polymers. That is, such polymers can tolerate lower levels of hydroxyethyl groups and, as a result, are less hygroscopic and do not have as severe a caking problem as the polymers of Landoll, and are easier to process and use.